Influenza (flu) viruses change continuously, therefore also the parts of viruses used in influenza vaccines can vary from year to year. In Europe, manufacturers/marketing holders of these vaccines are required to be involved in ongoing clinical trials and to present the results to the competent authorities each year. The current study is a phase IIIa clinical trial with a commercially available vaccine (Influvac®) supplied in pre filled syringes. It is part of the ongoing clinical trial program for Influvac® and will be done to assess the immunogenicity and safety and tolerability of next season's trivalent influenza subunit vaccine in two groups of healthy subjects: subjects aged >= 18 and <= 60 years and subjects >= 61 years of age (elderly).

Inclusion Criteria:

• Signed and dated informed consent.
• Healthy and aged >= 18 and <= 60 years or >= 61 years of age.
• Mental health good enough to understand the study and the informed consent form and to fill in the questionnaire.

Exclusion Criteria:

• Known to be allergic to eggs, chicken protein, gentamicin or any other constituent of the vaccine.
• Having fever and/or presenting with an acute infectious episode of the upper and/or lower respiratory airways.
• Having experienced a serious systemic and/or local reaction after previous influenza vaccination.
• Having an auto-immune disorder (e.g. RA, SLE, auto-immune thyroid disorders) or other disorders affecting the immune system, taking immunosuppressive medication (such as systemic corticosteroids) including the four weeks preceding the start of the study (date of informed consent), or having a disease in a terminal stage.
• Having received vaccination against influenza within the previous six months before Visit 1.